1. Field of the Invention
The present invention relates to holder/optical-element assemblies in which an optical element is integrated with a holder, and particularly, to a holder/optical-element assembly formed by press-molding an optical-element material.
2. Description of the Related Art
Optical elements, such as lenses used in digital cameras and in pickup heads of CD players, require high precision when installed. As disclosed in, for example, Japanese Patent No. 2729702, a substantially—precise installation is generally achieved by forming a holder/optical-element assembly, in which the optical element is held by the holder, and then adjusting a position of the holder during the installation. In this holder/optical-element assembly, the optical element is formed by setting an optical-element material within a cylindrical holder, heating the material until it softens, and then press-molding the softened material using a mold. In the above-described method, the optical element is formed and press-fitted to the holder in order to achieve an integration of the optical element with the holder.
When press-molding, if the optical-element material has a volume error, a thickness of the optical element may vary. This may not only deteriorate an optical quality of the optical element, but also may require adjustment and fixing to an appropriate optical position, thus causing potential problems in terms of optical performance and positioning.
To minimize these problems, a method is provided for reducing volume errors by improving a volume precision of the optical-element material. To increase the effect of this method, however, improvement is sought in the precision of not only the volume of the optical-element material but also a formation of the holder.